JP2008042479A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact piezoelectric device having excellent characteristics. <P>SOLUTION: The present invention relates to a piezoelectric device comprising a substrate 20, an electronic component 40 disposed on an upper face 20a of the substrate 20 and a piezoelectric vibrator disposed at an upper side of the electronic component 30, wherein the piezoelectric vibrator is supported by a plurality of supporting members 60 bonded onto the substrate 20. Among the plurality of supporting members 60, at least members 60a, 60b are provided between two pads 55, 56 on the upper face 20a of the substrate 20, at other than four corners of the substrate 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric device in which a substrate, an electronic component, and a piezoelectric vibrator are arranged in this order.

Piezoelectric devices are widely used in small information devices such as HDDs (hard disk drives), mobile computers, and IC cards, and mobile communication devices such as mobile phones, car phones, and paging systems.
FIG. 7 is a side view of a conventional piezoelectric device 1 and is a diagram showing an internal structure with a part cut away (see, for example, Patent Document 1).

As shown in this figure, the piezoelectric device 1 includes a substrate 2, an electronic component 3, and a piezoelectric vibrator 4 in order from the bottom.
That is, a support member 7 is provided on the upper surface of the substrate 2, the piezoelectric vibrator 4 is mounted on the support member 7, and a space S is formed between the piezoelectric vibrator 4 and the substrate 2, The electronic component 3 is arranged in the space S.

In addition, the substrate 2 has a plurality of pad portions 6 electrically connected to the electronic component 3 on the upper surface thereof. The pad portion 6 is electrically connected to the mounting terminal 5 via a wiring pattern (not shown) on the substrate 2. Further, the pad portion 6 is electrically connected to the piezoelectric vibrator 4 via a conductive portion 8 provided on the support member 7.
As described above, the piezoelectric device 1 is mounted by arranging the substrate 2, the electronic component 3, and the piezoelectric vibrator 4 in the height direction as compared with the case where the electronic component 3 and the piezoelectric vibrator 4 are arranged side by side. The area is reduced.

Japanese Patent Laid-Open No. 2002-64333

By the way, in recent years, downsizing of electronic devices and the like is rapidly progressing, and further downsizing of piezoelectric devices used in the electronic devices is required.
However, since the piezoelectric device 1 as shown in FIG. 7 is configured to support the piezoelectric vibrator 4 with the support member 7, the length L of the piezoelectric device 1 is increased by the width W of the support member 7. I have to.
The mounting terminals 5 are provided at the four corners in order to place the piezoelectric device 1 horizontally on the mounting substrate, but support members 7 are provided at the four corners of the upper surface of the substrate 2. For this reason, the distance of the wiring pattern (not shown) for electrically connecting the mounting terminal 5 and the pad portion 6 on the upper surface of the substrate 2 is increased, and the stray capacitance is increased, which adversely affects the characteristics. There is a fear.

  An object of the present invention is to provide a piezoelectric device that is downsized and has excellent characteristics.

  According to the first invention, the above-mentioned object is a piezoelectric device comprising a substrate, an electronic component disposed on the upper surface of the substrate, and a piezoelectric vibrator disposed above the electronic component, The piezoelectric vibrator is supported by a plurality of support members bonded to the substrate, and at least a part of the plurality of support members is located at a position other than the four corners of the substrate, and is on the upper surface of the substrate. This is achieved by a piezoelectric device provided between two pad portions arranged side by side.

According to the configuration of the first invention, at least a part of the plurality of support members for supporting the piezoelectric vibrator is between the two pad portions arranged on the upper surface of the substrate at a position other than the four corners of the substrate. Is provided. Therefore, the space between the pad portions arranged side by side can be effectively used to contribute to space saving.
Moreover, since the supporting member is arrange | positioned other than the four corners of a board | substrate, a pad part can be arrange | positioned at the corner | angular part of a board | substrate. For this reason, it is possible to shorten the wiring between the pad portion at the upper side corner of the substrate and the mounting terminal at the mounting side corner by using a via hole, for example, and to suppress factors that adversely affect characteristics such as stray capacitance. .
Thus, according to the first invention, it is possible to provide a piezoelectric device that is miniaturized and has excellent characteristics.

According to a second invention, in the configuration of the first invention, the electronic component is a semiconductor element having a circuit structure for oscillating at least the piezoelectric vibrator, and the corner of the substrate is inserted with the semiconductor element. An input / output pad portion electrically connected to the output terminal is provided.
According to the configuration of the second invention, the corner portion of the substrate is provided with the input / output pad portion that is electrically connected to the input / output terminal of the semiconductor element. That is, according to the first invention, the support members are no longer arranged at the four corners of the substrate, so that the input / output pad portions can be placed at the corner portions as in the second invention. The input / output pad portion is a portion where stray capacitance is particularly likely to occur. However, as with the first invention, the problem of stray capacitance can be effectively solved.

According to a third aspect of the present invention, in the configuration of the first or second aspect, the pair of support members among the plurality of support members is arranged in accordance with a position of the external terminal portion of the piezoelectric vibrator. And
According to the configuration of the third invention, the pair of support members are arranged in accordance with the position of the external terminal portion of the piezoelectric vibrator. Therefore, if the piezoelectric vibrator is connected to the support member, the external terminal portion and the electronic component can be electrically connected via the conductive portion provided on the support member. In addition, the wiring for electrically connecting the external terminal portion and the electronic component can be shortened to reduce problems such as stray capacitance.

According to a fourth invention, in any one of the first to third inventions, the support member is formed of a non-conductive member.
According to the structure of 4th invention, the supporting member is formed with the nonelectroconductive member. For this reason, for example, when wire bonding is performed between the electronic component and the pad portion on the substrate, there is no short circuit even if the wire contacts the support member. In particular, when a molten resin is filled to mold the resin between the substrate and the piezoelectric vibrator, the wire pressed by the resin is likely to come into contact with the support member. Short circuit due to contact between the wire and the support member can be prevented.

1 to 4 show a piezoelectric oscillator 10 as an example of a piezoelectric device according to an embodiment of the present invention. FIG. 1 is a schematic plan view of the piezoelectric oscillator 10 and FIG. 2 is a schematic cut along line AA in FIG. FIG. 3 is a schematic bottom view of the piezoelectric oscillator 10 and FIG. 4 is a schematic plan view seen through the piezoelectric vibrator.
For convenience of understanding, FIGS. 2 and 4 show the inside of a resin 50 to be described later in a transparent manner, and FIG. 2 does not show all the bonding wires.

In these drawings, the piezoelectric oscillator 10 includes a substrate 20, an electronic component 40 disposed on the upper surface 20 a of the substrate 20, and a piezoelectric vibrator 30 disposed on the upper side of the electronic component 40.
As shown in FIGS. 1 and 2, the piezoelectric vibrator 30 is a surface-mount type vibrator having a rectangular package 38 in which an internal space S1 is formed.

Specifically, the package 38 is formed by laminating a plurality of substrates 38a and 38b formed by molding an aluminum oxide ceramic green sheet and then sintering.
In addition, on the inner bottom surface exposed to the internal space S1 of the package 38, for example, an electrode portion 31 formed by nickel plating and gold plating on a tungsten metallization is provided.
As shown in FIG. 1, a pair of electrode portions 31 are provided at both ends in the width direction of the piezoelectric vibrator 30, and each is electrically connected to an external terminal portion 35 provided on the outer bottom surface of the package 38. ing. Note that a pair of external terminal portions 35 are also provided at both ends of the piezoelectric vibrator 30 in the width direction, although not shown.

In addition, a piezoelectric adhesive piece 36 is bonded and fixed to the upper surface of the electrode portion 31 using a conductive adhesive 37.
The piezoelectric vibrating piece 36 is formed of, for example, quartz, and a piezoelectric material such as lithium tantalate can be used in addition to quartz. Here, in order to reduce the size, an AT-cut vibrating piece obtained by cutting a quartz wafer in a predetermined direction is used. However, the present embodiment is not limited to this, and for example, a so-called tuning-fork type vibrating piece may be used.

Further, as shown in FIG. 2, a lid 34 is joined to the open end surface of the package 38 using a brazing material 33, and the internal space S1 is sealed.
The lid 34 irradiates a metal coating portion (not shown) of the piezoelectric vibrating piece 36 with a laser beam from the outside and adjusts the frequency by a mass reduction method. It is formed or made of metal for grounding.

In the case of this embodiment, the electronic component 40 is a semiconductor element having at least a circuit structure that oscillates the piezoelectric vibrator 30, and preferably, temperature compensation data corresponding to the characteristics of the piezoelectric vibrator 30 is written. It has become.
Specifically, the electronic component 40 is bonded and fixed to the upper surface 20 a of the flat substrate 20. Further, the electronic component 40 has a rectangular shape having an outer shape smaller than the outer shape of the piezoelectric vibrator 30 in the horizontal direction, and is disposed so as to overlap the inside of the piezoelectric vibrator 30 in a plan view.

As shown in FIG. 4, the electronic component 40 is provided with a plurality of terminal portions 41, 42, 43, 44 only on one side of the main surface (upper surface in FIG. 2).
Of course, the number and types of terminal portions of the electronic component 40 may be larger or smaller than those shown in FIG. 4 depending on the type of the semiconductor element, but in the present embodiment, the mounting terminal portions 62 ( In order to write data to the input / output terminal 41 of the oscillation circuit connected to the piezoelectric circuit 30, the gate / drain (G / D) terminal 44 electrically connected to the piezoelectric vibrator 30, and the electronic component 40. Control terminal 42 and ground terminal 43.

The terminal portions 41, 42, 43, and 44 of the electronic component 40 are electrically connected to the pad portions 55, 56, 57, and 58 on the substrate 20 by wire bonding.
That is, the plurality of terminal portions 41, 42, 43, 44 and predetermined pad portions 55, 56, 57, 58 to be wire-bonded on the substrate 20 described later are arranged as close as possible to each other. The terminal portions of the embodiment are arranged side by side at both ends in the width direction of the electronic component 40.

  The substrate 20 is a member that interposes the electronic component 40 and the piezoelectric vibrator 30 so as to overlap each other in the vertical direction and electrically connect them, and the base material is formed of an insulating member such as ceramic or polyimide. A flat rigid substrate or a flexible substrate can be used. The substrate 20 of this embodiment is formed so that the horizontal outer shape is substantially the same as the horizontal outer shape of the piezoelectric vibrator 30.

As shown in FIG. 4, a plurality of pad portions 55, 56, 57, 58 are provided on the upper surface 20 a of the substrate 20 by printing, vapor deposition, plating, or the like.
The pad portions 55, 56, 57, and 58 are electrodes for conducting electrical connection between the piezoelectric vibrator 30 and the electronic component 40 and electrical terminals between the electronic component 40 and each terminal on the mounting surface. That is, as shown in FIGS. 3 and 4, the pad portion 55 is an input / output pad portion wire-bonded to the input / output terminal 41 of the electronic component 40, and is provided on the lower surface (mounting surface) 20b of the substrate 20. The mounting terminal 62 is electrically connected. The pad portion 56 is a control pad portion that is wire-bonded to the control terminal 42 of the electronic component 40, and is electrically connected to the control terminal 65 provided on the lower surface (mounting surface) 20 b of the substrate 20. The pad portion 57 is wire-bonded to the ground terminal 43 of the electronic component 40, is electrically connected to the terminal 63 provided on the lower surface (mounting surface) 20b of the substrate 20, and is grounded. The pad portion 58 is wire-bonded to the gate / drain (G / D) terminal 44 of the electronic component 40, and is piezoelectric via a wiring pattern 59 and a conductive portion in a via hole 61 (see FIG. 2) of the support member 60 described later. The vibrator 30 is electrically connected.

Further, a plurality of support members 60,... Are bonded to the upper surface 20a of the substrate 20, and the piezoelectric vibrator 30 is supported by the plurality of support members 60,. Thus, the piezoelectric vibrator 30 is positioned, and a space S <b> 2 is formed between the piezoelectric vibrator 30 and the substrate 20 to accommodate each component such as the electronic component 40 and the wire.
The space S2 between the piezoelectric vibrator 30 and the substrate 20 is resin-molded so that the piezoelectric vibrator 30 is securely fixed and each component such as the electronic component 40 and the bonding wire is protected. . That is, an insulating member such as an epoxy resin is injected into the space S2 using a mold, or the resin is filled by screen printing.

Here, at least some of the plurality of support members 60 that support the piezoelectric vibrator 30 are arranged at the positions other than the four corners of the substrate 20 on the upper surface 20a of the substrate 20. It is provided between the pad portion 55 and the pad portion 56.
Specifically, for example, the lower support member 60 in FIG. 4 will be described. Among the plurality of pad portions 55, 56, 57 arranged in a row, some pad portions (hereinafter referred to as “control pad portions”). 56) is moved closer to the pad portion 57 side opposite to the input / output pad portion 55, and a predetermined distance L1 is provided between the control pad portion 56 and the input / output pad portion 55. Then, within this predetermined interval L1, a region connecting the pad portions 55, 56, 57, 58 and the terminal portions 41, 42, 43, 44 (ie, a region where wire bonding is performed) is avoided. Thus, the support member 60b is arranged.

  Further, the interval L1 between the control pad portion 56 and the input / output pad portion 55 has a sufficient interval so that the support member 60b can be formed long. That is, although the support member 60b is a member for supporting the piezoelectric vibrator 30, it is preferable to secure an area as much as possible because it is not disposed at the four corners. However, if the support member 60b has a width larger than the width W1 of the pad portions 55 and 56, the entire piezoelectric device becomes large. Therefore, the support member 60b is formed so as to have substantially the same width as the pad portions 55 and 56. Yes.

The support member 60b is not disposed at the corner portion of the substrate 20 as described above, but is disposed between the input / output pad portion 55 and the control pad portion 56, whereby the input / output pad portion 55 is disposed on the substrate 20. The input / output pad portion 55 can be disposed immediately above the mounting terminal 62.
Note that the upper support member 60a in FIG. 4 has substantially the same configuration as that of the lower support member 60b, and a description thereof will be omitted.

  In the case of this embodiment, among the plurality of support members 60,..., The pair of support members 60c, 60d are aligned with the positions of the pair of external terminal portions 35 of the piezoelectric vibrator 30 as shown in FIG. Are arranged. The pair of support members 60c and 60d have a conductive portion in the via hole 61, and the conductive portion is connected to the metal film portion 67 formed on the end face on the piezoelectric vibrator 35 side. Thus, when the piezoelectric vibrator 30 is placed on the support member 60, the external terminal portion 35 and the metal film portion 67 formed on the end face can be connected to face each other.

The plurality of support members 60,... Are columnar and are formed of non-conductive members.
FIG. 5 is a diagram illustrating a manufacturing process for forming the support member 60.
That is, as shown in FIG. 5 (a), a ceramic frame-like member 70 having a frame portion 71 and projections 72 that protrude toward the inside of the frame portion 71 at a predetermined interval. First prepare. At this time, a flat ceramic substrate 74 is also prepared.

  The substrate 74 and the frame-shaped member 70 have dimensions capable of forming the plurality of substrates 20 and the support member 60 at a time, and the protrusion 72 of the frame-shaped member 70 is a cutting process described later. Then, the support member 60 (see FIGS. 2 and 4) is formed, and has the same height and positional relationship as the support member 60 described above. Moreover, the board | substrate 74 turns into the board | substrate 20 (refer FIG. 2, FIG. 4) through the cutting process mentioned later.

Then, the frame-shaped member 70 is stacked on the upper surface of the substrate 74 and fired to join the frame-shaped member 70 and the substrate 74 together.
Next, as shown in FIG. 5 (b), the portion shown by the dotted lines of the substrate 74 and the frame-shaped member 70 so as to be slightly inside the frame portion 71 so that the frame portion 71 and the protrusion 72 are separated from each other. And a state in which the support member 60 is bonded to the substrate 20 is formed.

The embodiment of the present invention is configured as described above, and at least some of the plurality of support members 60 for supporting the piezoelectric vibrator 30 have portions 60 a and 60 b at positions other than the four corners of the substrate 20. Are provided between the two pad portions 55 and 56 arranged on the upper surface 20a. Therefore, it is possible to save space by effectively utilizing the space between the pad portion 55 and the pad portion 56 arranged side by side. That is, as shown in FIG. 4, the electronic component 40 can be disposed close to one side of the square substrate 20, and the entire piezoelectric oscillator 10 can be reduced in size.
Further, since the support member 60 is disposed at other than the four corners of the substrate 20, the pad portion 55 can be disposed at the corner portion of the substrate 20. For this reason, for example, the wiring for electrically connecting the pad portion 55 at the corner on the upper surface side and the mounting terminal 62 at the corner portion on the mounting surface side is shortened to cause adverse effects on characteristics such as stray capacitance Can be eliminated.

  In addition, as shown in FIG. 6 which is a schematic longitudinal cross-sectional view concerning the modification of embodiment mentioned above, this invention uses the metal ball for the supporting member 60, and conduct | electrically_connects with the electronic component 40 and the external terminal part 35. As shown in FIG. You may make it show. Further, a non-conductive member may be used as the support member 60 to prevent a short circuit when a bonding wire comes into contact with the support member 60. In particular, when the molten resin is filled between the substrate 20 and the piezoelectric vibrator 30 and resin molding is performed, since the wire pressed by the resin is likely to come into contact with the support member 60, the support member 60 is not electrically conductive. The effect of making a sex member is great.

The present invention is not limited to the above-described embodiment. Each configuration of the embodiment and each modified example can be appropriately combined or omitted, and can be combined with other configurations not shown.
For example, among the plurality of support members 60, the support members 60a and 60b shown in FIG. 4 are non-conductive members, and only the pair of support members 60c and 60d aligned with the positions of the pair of external terminal portions 35 are shown in FIG. A metal ball as shown in FIG.

It is an illustration of the piezoelectric device which concerns on embodiment of this invention, and is a schematic plan view of a piezoelectric oscillator. FIG. 2 is a schematic sectional view taken along line AA in FIG. 1. 1 is a schematic bottom view of a piezoelectric oscillator, which is an example of a piezoelectric device according to an embodiment of the present invention. FIG. 4 is a schematic plan view illustrating a piezoelectric device according to an embodiment of the present invention as seen through a piezoelectric vibrator. The figure for demonstrating the process of forming a supporting member. The schematic longitudinal cross-sectional view which concerns on the modification of embodiment of this invention. It is the side view of the conventional piezoelectric device, and the figure which notched one part and showed the internal structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Piezoelectric device (piezoelectric oscillator), 20 ... Board | substrate, 30 ... Piezoelectric vibrator, 40 ... Electronic component (semiconductor element), 41, 42, 43, 44 ... Terminal part, 55 , 56, 57, 58... Pad part, 60, 60a, 60b, 60c, 60d.

Claims (4)

A piezoelectric device comprising a substrate, an electronic component disposed on the upper surface of the substrate, and a piezoelectric vibrator disposed on the upper side of the electronic component,
The piezoelectric vibrator is supported by a plurality of support members bonded to the substrate,
At least a part of the plurality of support members is provided at a position other than the four corners of the substrate between two pad portions arranged on the upper surface of the substrate. The electronic component is a semiconductor element having a circuit structure for oscillating at least the piezoelectric vibrator,
2. The piezoelectric device according to claim 1, wherein an input / output pad portion electrically connected to an input / output terminal of the semiconductor element is provided at a corner portion of the substrate.   3. The piezoelectric device according to claim 1, wherein the pair of support members among the plurality of support members is arranged in accordance with a position of an external terminal portion of the piezoelectric vibrator.   The piezoelectric device according to claim 1, wherein the support member is formed of a non-conductive member.

Images